The first reason why the sound can lag behind video track usually is the incorrect recording of the movie copy. If the sound lags when playing a particular clip, but all other video files played on your computer properly, it is likely that the problem lies in this file. Try to download another copy of this video, in which audio and video are correctly synchronized.
The delay in sound reproduction video can be caused by insufficient capacity of your equipment. This means that the computer or its operating system is unable to cope with the processing of the video that is causing some delays – the video quality is too high for your device. To try to avoid the problem, try another program for playback or upload the same video but the quality is worse. You can also try to play a video file on another computer.
Audio delay in video can be caused by the wrong operation of the software image processing. To fix the problem try to uninstall your current version of third-party codecs installed on your system. To do this go to "start" - "control Panel" - "Uninstall programs" and delete the corresponding menu item. Then go to the Internet site to download the codecs and output them to download or install.
It is likely that the cause of the problems in the video playback may be improper functioning of hard drive. Go to "control Panel" - "System" - "Hardware" - "device Manager" - "Disk controllers". In the proposed list, select the name of your ROM and go to the Policies tab, where you tick the box next to "Enable enhanced performance". Reboot the system and try playing your video again.